I'm unclear specifically what you're asking, but I can tell you each of them has a new skin (does not need to be unlocked) that comes in I think 3 colors, each one named uniquely. They do not have a rarity attached and they don't say anything like Found in the Krypt or anything, they're just there at the end of Scorp / Sub / Noob's list. Shang similarly has two skins (the movie ones) that lack rarity and locations, they're just unlocked. I would assume johnny is the same.
The gear, on the other hand I do not think is as obvious or unlocked. Shang MUST have come with a few items unlocked because I have about 10 things already, but the ninjas I do not think anything new unlocked for free, there were definitely new selections in the menu, but again, they added a bunch of stuff in the patch so no way to tell.
From my tracking, Shang Tsung came with the following:
Skins: Spirit Stealer & Force of Darkness
Bracers: Touch of Death
Ancient Scrolls: Brownback Dragon Spells
Soul Phylactery: Soulsnake Oil
Now, the Skins appear to be Kombat Pack Exclusives, as shown here:
https://testyourmight.com/threads/psa-shang-tsung’s-movie-skin-is-exclusive-to-kombat-pack-owners-more-exclusives-possible.70860/
Will the three gear pieces listed above also be Kombat Pack Exclusive? We'll know next week if purchasers of Shang Tsung without the Kombat pack get them as well. Personally, I think they will be, because I noticed when downloading Shang Tsung, it had it listed as "Shang Tsung - Kombat Pack Version."
As for the Kombat Pack being "overpriced," as others have mentioned, OP doesn't seem to be taking into account the fact that, with the Kombat Pack, you are getting exclusive skins, in addition to getting other items besides just the characters. Even if you go by his guess of $6 per character, does anyone honestly think that, when the Klassic Arcade Ninja Skin Pack is released for non-Kombat Pack owners, it will cost less than the predicted $4 difference? I don't. If I had to guess, the cost of the Ninja Skin Pack alone will be $5. Kombat Pack owners got that as part of the Kombat Pack.
That's not even taking into account the Beta Access Kombat Pack owners got (which some were willing to pay more than $5 for during the beta, so it certianly had value to some).
Now, some may say skins and/or gear aren't "worth" the extra money, but, like the Beta Access, they obviously have value to some people. If they don't to you and all you want is the 6 characters then the Kombat Pack MAY be a couple bucks more than JUST the 6 characters, assuming that the OP is right and characters are $6 each.
However, if they end up being $7 or more each, You'll actually end up spending MORE and get less for just the 6 characters than if you had bought the Kombat Pack.